Consider mountain laurel (Kalmia) which may be relatively vase-shaped depending on the cultivar your choose. I don't know how it does with real powder-soil type of dryness, but I grow several in shade in a well-drained bed that isn't within hose reach so they have gotten no water since the year of planting that hasn't fallen from the sky, including last summer's drought.

Thanks, NHBabs, that's one I hadn't thought of that I will consider. It's a tough spot under a maple tree but I'd really like to get some screening there. Hearing that yours have done well with drought is helpful!

A few observations:

Pro's:

They do well in a wide range of light levels and flower well in shade, partial and almost just full sun. The fuller sun plants have thicker foliage/blooms but the nearly full shade plants still have beautiful blooms. They form huge stands here in the understory that are amazing.

In the almost 2 years I've been here I've never fertilized or watered them and they seen happy.

Cons:

They are a little leggy and the foliage isn't as dense as your typical backyard shrub. They're sparse enough not to shade out weeds underneath but woody and dense enough to make weeding a pain.

On my location(see pic), they are affected by some infection that marrs the leaves but doesn't seem to hurt the plant otherwise. This makes the winter foliage a little less appealing as there are many red-white dots on the leaves. The new flush of leaves in the spring are healthy but they slowly get attacked by winter.

All in all I love them. The forming flower buds are almost better than the flowers. Just keep in mind you won't get the same winter splash as say a coniferous evergreen shrub.

Here is another one from my yard. Sorry the lighting isn't great but you can see the sparse look I'm trying to explain.

Thanks Dtunesgw, your mountain laurels are beautiful! I love them too and agree about the great buds. In this location leggy might be okay because there's a fence but I want screening above. Since they carry most of the foliage at the top it could work. Thanks for the suggestions and photos!